a. Field of the Invention
This invention relates to salts of the fluorescent compounds 4,4'-bis(4-anilino-6-morpholino-s-triazin-2-ylamino)-2,2'-stilbenedisulfon ic acid and 4,4'-bis(4,6-dianilino-s-triazin-2-ylamino)-2,2'-stilbenedisulfonic in acid novel crystalline forms having improved properties as optical bleaching agents, to new articles of manufacture containing said salts in the novel forms, to detergent compositions containing said salts in the novel forms, and to the preparation of same.
B. Description of the Prior Art
Disodium 4,4'-bis(4-anilino-6-morpholino-s-triazin-2-ylamino)-2,2'-stilbenedisulfon ate (Formula I) ##STR1## and disodium 4,4'-bis(4,6-dianilino-s-triazin-2-ylamino)-2,2'-stilbenedisulfonate (Formula II) ##STR2## are known compounds which have valuable properties as fluorescent optical bleaching agents in detergent compositions for the laundering of textile goods. The dianilino-, dimorpholino-substituted compound of Formula I, its preparation and utility as an optical bleach have been described, for example, in U.S. Pat. No. 2,612,501, patented Sept. 30, 1952. Similarly, the tetra-anilino-substituted compound of Formula II, its preparation and utility as an optical whitening and brightening agent have been described in the prior art, for example, in Japanese Pat. No. 3988/51, issued July 24, 1951, and in German Auslegeschrift 1,100,583, issued Mar. 2, 1961. The prior art teaches that these compounds are ordinarily prepared in the following manner. One molecular proportion of disodium 4,4'-diaminostilbene-2,2'-disulfonate is condensed with two molecular proportions of cyanuric chloride at low temperature (0-5.degree. C); then, in the case of the compound of Formula I, one molecular proportion of the resulting disodium 4,4'-bis(4,6-dichloro-s-triazin-2-ylamino)-2,2'-stilbenedisulfonate is aminated with two molecular proportions of aniline or morpholine at approximately 50.degree. C; and one molecular proportion of the resulting product, that is, disodium, 4,4'-bis(4-chloro-6-anilino-s-triazin-2-ylamino)-2,2'-stilbenedisulfonate or disodium 4,4'-bis(4-chloro-6-morpholino-s-triazin-2-ylamino)-2,2'-stilbenedisulfona te is aminated at 95.degree.-100.degree. C with two molecular proportions of either morpholine or aniline, respectively, to produce disodium 4,4'-bis(4-anilino-6-morpholino-s-triazin-2-ylamino)-2,2'-stilbenedisulfon ate. In the case of the compound of Formula II, the intermediate disodium 4,4'-bis(4,6-dichloro-s-triazin-2-ylamino)-2,2'-disulfonate is interacted with aniline at a somewhat higher temperature (usually in the range 30.degree.-100.degree. C) to replace the four chloro substituents with four aniline groups. In each of these steps, sufficient alkali is added to the reaction mixture to keep it substantially neutral during the reaction.
As produced by this known method of manufacture, the disodium 4,4'-bis(4-anilino-6-morpholino-s-triazin-2-ylamino)-2,2'-stilbenedisulfon ate is a pale yellow amorphous (non-crystalline) solid. This amorphous product has the drawback of being light-sensitive, changing from yellow to green to brown during relatively short exposures to light, for instance, one to two hours. The light sensitivity is objectionable, especially when the product is to be incorporated into white detergents. As produced by the known method of manufacture, disodium 4,4'-bis(4,6-dianilino-s-triazin-2-ylamino)-2,2'-stilbenedisulfonate is a yellow solid which is usually marketed and used in the light-sensitive amorphous form in which it is initially obtained by the above method or, in some instances, the amorphous form has been converted into a yellow crystalline form consisting predominantly of a plate-like crystalline form. Furthermore, German Auslegeschrift 1,100,583 discloses a method for producing the compound in the form of a mixture of plates and crystalline rods or needles which is yellow and undesirable for the manufacture of detergent compositions. When any of these forms of the product is incorporated into detergent compositions, it has the drawback of poor resistance to chemical attack by the hypochlorite bleach commonly added during laundering, so that a substantial proportion of the whitening and brightening effect is destroyed. Moreover, in many instances, it has been found that they impart an undesirable yellow cast to white solid detergent compositions.